In the modern commercialized and industrialized society where international business and leisure travels occur frequently, a user who uses personalized portable electrical appliances, such as a mobile phone, a battery charger, and a chargeable electrical shaver, may need to travel to various countries or areas of the world. The electrical power supplied in different countries and the specifications of the wall sockets in different countries may be different, so that a single charging plug is certainly not suitable for different countries. Due to this reason, a user must carry a few electrical adapters that meet the specifications of electrical power supplied and the wall sockets when he or she is traveling abroad. However, each individual electrical adapter currently available in the market only suit for use in a specific country or area, and thus a user must purchase a new adapter corresponding to a different foreign country where he or she is going to visit, and the newly purchased adapter may not be useful in the next travel to another foreign country. This is a troublesome problem. Thus, manufacturers are providing products of adapter that comprise parent and child plugs for different socket specifications.